Properties of Matter  What makes states of matter different from each other? Objective: I will be able to: describe substances based on physical and chemical properties.

Properties of Matter Understanding matter begins with observation. What you observe when you look at a particular sample of matter is its properties. Is a solid shiny or dull? Does a liquid flow quickly or slowly? Is a gas odorless or does it have a smell? Is the texture rough or smooth?

Matter Properties used to describe matter can be classified as extensive or intensive. Recall that matter: is anything that has mass and takes up space. The mass: of an object is a measure of the amount of matter an object contains. The mass of a bowling ball with finger holes is five or six times greater than the mass of the bowling ball shown in Figure 2.1, which is used to play a game called candlepins. There is also a difference in the volume of the balls. Mass and volume are examples of extensive properties.

Extensive Properties The volume: of an object is a measure of the space occupied by an object. An extensive property: is a property that depends on the amount of matter in a sample.

Intensive Properties There are properties to consider when selecting a bowling ball other than mass. Beginning bowlers want a bowling ball that is likely to maintain a straight path. They use bowling balls with a hard surface made from polyester. Experienced bowlers want a bowling ball they can curve, or hook, toward the pins. Often, they use a polyurethane ball, which has a softer surface. Hardness is an example of an intensive property. An intensive property: is a property that depends on the type of matter in a sample, not the amount of matter.

Properties of Matter Extensive Intensive Mass: A measurement of the amount of matter present in an object. Weight: A measurement of the gravitational force of attraction of the earth acting on an object. It is given by product of the mass of the object by the acceleration due to gravity W = m * g. The SI unit is Newton (N) or kilogram-meters per second squared. Volume: A measurement of the amount of space a substance occupies. Volume is the space actually occupied by an object or the bulk of some substance. Length: The linear extent in space from one end to the other. The SI unit of length is meter (m). Intensive Color: Perception of the different wavelengths of light. Odor: Perception of the sense of smell. Luster: Shininess of surface. Almost all metals have a shining surface. Malleability: The ability of a substance to be beaten into thin sheets. Ductility: The ability of a substance to be drawn into thin wires. Conductivity: The ability of a substance to allow the flow of energy or electricity. Metals like copper, bronze, steel are good conductor of heat and electricity. Hardness and softness: This is how easily a substance is scratched. A diamond is the hardest substance known, iron and aluminum are hard while magnesium is a soft metal. Density: The mass of a substance divided by its volume D = Mass/Volume. Pressure: The force per unit area. The standard unit for pressure is the Pascal (Newton per square 

Matter Each object to the right has a different chemical makeup, or composition. The sculpture of a falcon is mainly gold. The kettles are mainly copper. substance: matter that has a uniform and definite composition Gold and copper are examples of substances, which are also referred to as pure substances. Every sample of a given substance has identical intensive properties because every sample has the same composition.

Matter Gold and copper have some properties in common, but there are differences besides their distinctive colors. Pure copper can scratch the surface of pure gold because copper is harder than gold. Copper is better than gold as a conductor of heat or electric current. Both gold and copper are malleable, which means they can be hammered into sheets without breaking. But gold is more malleable than copper.

Matter Hardness, color, conductivity, and malleability are examples of physical properties. A physical property: is a quality or condition of a substance that can be observed or measured without changing the substance’s composition.

Matter The states of the substances are given at room temperature (23°C). Physical properties can help chemists identify substances. For example, a colorless substance that was found to boil at 100°C and melt at 0°C would likely be? A colorless substance that boiled at 78°C and melted at −117°C would most certainly a different substance. Based on the table at the right, it would likely be?

 Compare & contrast extensive and intensive properties.

Matter Depending on the circumstances, you use three different words to refer to water— water, ice, and steam. Water, which is a common substance, exists in three different physical states. So can most other substances. Three states of matter are solid, liquid, and gas. Certain characteristics that can distinguish these three states of matter are summarized in Figure 2.3 on the next slide.

Matter

Solids A solid: is a form of matter that has a definite shape and volume. The shape of a solid doesn’t depend on the shape of its container.

Solids The particles in a solid are packed tightly together, often in an orderly arrangement, as shown in the figure. As a result, solids are almost incompressible; that is, it is difficult to squeeze a solid into a smaller volume. In addition, solids expand only slightly when heated.

Liquids The particles in a liquid are in close contact with one another, but the arrangement of particles in a liquid is not rigid or orderly.

Liquids Because the particles in a liquid are free to flow from one location to another, a liquid takes the shape of the container in which it is placed. However, the volume of the liquid doesn’t change as its shape changes. The volume of a liquid is fixed or constant. Thus, a liquid: is a form of matter that has an indefinite shape, flows, yet has a fixed volume. Liquids are almost incompressible, but they tend to expand slightly when heated.

Gases Like a liquid, a gas takes the shape of its container. But unlike a liquid, a gas can expand to fill any volume. A gas: is a form of matter that takes both the shape and volume of its container. The words vapor and gas are sometimes used interchangeably. But there is a difference. The term gas is used for substances, like oxygen, that exist in the gaseous state at room temperature. (Gaseous is the adjective form of gas.) Vapor: describes the gaseous state of a substance that is generally a liquid or solid at room temperature, as in water vapor.

Gases As shown in the model, the particles in a gas are usually much farther apart than the particles in a liquid. Because of the space between particles, gases are easily compressed into a smaller volume.

Physical Change The melting point of gallium metal is 30°C. The picture at the right shows how heat from a person’s hand can melt a sample of gallium. The shape of the sample changes during melting as the liquid begins to flow, but the composition of the sample does not change. Melting is an example of a physical change. During a physical change: some properties of a material change, but the composition of the material does not change.

Physical Change Words such as boil, freeze, melt, and condense are used to describe physical changes. So are words such as break, split, grind, cut, and crush. However, there is a difference between these two sets of words. Each set describes a different type of physical change. Physical changes can be classified as reversible or irreversible.

Physical Change Melting is an example of a reversible physical change. If a sample of liquid gallium is cooled below its melting point, the liquid will become a solid. All physical changes that involve a change from one state to another are reversible. Cutting hair, filing nails, and cracking an egg are examples of irreversible physical changes.

 Pick a partner and discuss the following: What is a physical change? Give an example of a physical change Now, each of you find someone from another table and explain your partner’s example to them. Find a second person and explain it to them as well.

Chemical Properties Chemical properties: are any of the properties of matter that may only be observed and measured by performing a chemical change or chemical reaction. Chemical properties cannot be determined by touching or viewing a sample; the structure of the sample must be altered for the chemical properties to become apparent.

Chemical Properties reactivity with other chemicals toxicity coordination number flammability enthalpy of formation heat of combustion oxidation states chemical stability types of chemical bonds that will form

Chemical Change A chemical change produces a new substance (e.g., burning, rusting, photosynthesis) Recall - Physical Change does not produce a new substance (e.g., phase changes, crushing a can)

Chemical Change Solutions - result from combining two or more substances. Making a solution can produce either a physical or chemical change. You can tell them apart this way: The original substances can be separated from one another if the solution produces only a physical change. The original substances cannot be separated from one another if a chemical change took place.

Chemical Reaction A chemical reaction: the process that occurs when two or more substances combine to produce a chemical change. chemical equation: name given to the shorthand used to describe the steps of a chemical reaction reactants: the starting materials for a chemical reaction; the substances that combine in the reaction products: the substances that are formed as a result of a chemical reaction

 Chemical Equation What are the reactants? What are the products? What does the arrow mean?

Chemical Reactions chemical reaction rate: the speed at which a chemical reaction occurs activation energy: the external energy that has to be added in order for a chemical reaction to occur catalyst: a substance that helps a chemical reaction to occur (lowers the activation energy), but does not participate in the reaction itself

Conservation of Mass Law of Conservation of Mass - this Law states that matter is neither created nor destroyed in a chemical reaction. The number of reactant atoms of a chemical reaction will be the same as the number of product atoms. Antoine Lavoisier

 Pick a partner and discuss the following: What is a chemical change? Give an example of a chemical change Now, each of you find someone from another table and explain your partner’s example to them. Find a second person and explain it to them as well.

The law of conservation of mass - Todd Ramsey -TED Talk https://www.youtube.com/watch?v=2S6e11NBwiw